Standard backup tools often treat file metadata as an afterthought - backing up raw file contents while stripping away critical operating system attributes. Duplicati 2.4 addresses this cross-platform challenge by introducing deep metadata preservation, specifically targeting Windows Alternate Data Streams (ADS) and native macOS Access Control Lists (ACLs).

Windows Alternate Data Streams (ADS)

On NTFS file systems, Alternate Data Streams allow files to store multiple streams of data under a single handle. While the primary stream holds the file content (:$DATA), secondary streams store essential metadata, including "Mark of the Web" security flags (Zone.Identifier), custom file tagging, or proprietary database streams. Traditional file backups frequently drop these secondary streams during processing.

Duplicati 2.4 allows administrators to capture and restore every stream intact by enabling the --enable-ads-backup flag:

• Command Line Interface: Add --enable-ads-backup=true to your backup command execution.

  
  

• Web GUI: Navigate to Backup Configuration > Step 5 (Options) > Advanced Options, and select --enable-ads-backup.

  
  

When active, Duplicati serializes all non-default NTFS streams along with the primary payload. On restore, the full stream structure is reconstructed on the target volume without altering original file hashes.

macOS Native ACLs & Fine-Grained Permissions

Standard Unix POSIX permissions (rwxr-xr-x) fall short in managed macOS environments where granular access control is enforced. Enterprise macOS deployments rely heavily on Access Control Lists (ACLs) and extended attributes (xattr) to define inheritance rules, explicit group privileges, and application state metadata.

Duplicati 2.4 incorporates native Darwin API calls to read and restore these complex permission sets:

• Exact Access Replication: Preserves custom ACL definitions alongside xattr metadata (such as com.apple.quarantine flags).

  
  

• Zero-Script Restoration: Eliminates the need for post-restore chmod or chown remediation scripts when recovering user profiles or shared network volumes.

  
  

Cross-Platform Preservation Overview

By ensuring total fidelity across NTFS and macOS file attributes, Duplicati 2.4 gives system administrators complete confidence when managing sensitive, compliance-heavy file environments.